Walsh & Hoyt: Electro-Oculogram (EOG)

In 1848, Dubois-Reymond reported that a difference in electric potential of about 6 microvolts was present between the cornea and the back of the eye. It was subsequently appreciated that the human eye acts as a dipole, with the cornea positive with respect to the retina. If two electrodes are placed near the inner and outer canthi respectively, movement of the eye will produce a change in the potential measured between the two electrodes, with the electrode closest to the cornea being more positive. A recording of this potential change produced by movement of the eye is called the electro-oculogram. The EOG consists of two different potentials, one that is sensitive to light, and the other that is insensitive to light.